(Non)-Eternal
September's full moon granted certainty to a long-suspected fact: dementors were truly capable of holding back a werewolf. Their presence, however, also weakened the effects of the wolfsbane potion, which they learnt the hard way. But there were no casualties, so all was fine, as far as the two wizards and the three creatures were concerned.
Morning found the group in a small clearing of the Forbidden Forest. Sirius was sitting on a rock near the creek, watching an acromantula battle with Skipps. No matter how many times the dementor wrestled the huge spider into the ground, she still stood up and continued her attempt to devour the intruder.
"They're enjoying this leave just as much as I do," Padfoot whispered. "Skipps has never in his life been this far from Azkaban before."
"You talk like Hagrid," Moony remarked. "And that wasn't a compliment. Hey, speaking of pets. Do you know whom the Weasley kid is keeping? I'll give you one hint: a rat. I believe he's been a rat for over a decade."
Rage was Sirius's first reaction. 'Fully deserved' was the second. Then, "If you could just get us in during classes, I could clear myself! You are on sick leave today, aren't you, Moony?"
The Room of Requirement had much to offer to a cornered wizard. Chased by his betrayed friends, Pettigrew ran inside, and the first thing he'd found was a unicorn skull, complete with a huge horn. Panicked, he used that as a dagger... And impaled Daire with it.
Then, he morphed again and vanished among the junk. Moony and the two other dementors followed him in a hopeless chase.
Sirius fell on his knees next to his wounded keeper. He'd never before seen a dementor dying: the characteristic rattling breath became a series of clicks, the pale skin started to fade. The air turned icy as he attempted to take in as much energy as he could, which wasn't much. As his hood fell back, Sirius could only see emptiness inside. But even this close, in the greatest need, Daire refused to feed from an innocent. Not when Sirius was this close to regaining his freedom. No matter that he needed his strength, his hope.
Sirius looked around miserably. Had the Room of Requirement nothing to offer when they needed it?
A few steps away, he spotted something. It looked like few drops of molten gold at the bottom of a dusty bottle. Liquid Luck. He drank it without hesitation. Then, he shouted "Wait here!" and sprinted away to the far corner of the room. He returned with Rowena Ravenclaw's long-lost diadem between his fangs.
By then, Daire was lying flat, hardly more than an extremely cold black cloak. When Padfoot got back, however, he grabbed the jewelry and lifted it to his own mouth. Sirius only recognized the Kiss because he'd witnessed one just a few weeks before. What was this? A soul-piece, preserved for an emergency?
"We must tell Dumbledore!" he decided.